The invention relates generally to systems and methods for die casting, and more specifically to apparatus and methods for high-temperature directionally solidified and single-crystal die casting.
Certain metals and alloys have previously responded better to die casting while others are better cast using investment processes. Lower melting temperatures of aluminum-based and magnesium based alloys, for example, as well as favorable solidification pathways permitted the use of temperature resistant injection molds whereby the molten metal is solidified with a minimum of shrinkage or defects. Alloys with higher melting temperatures such as iron-based, titanium-based, nickel-based, and cobalt-based alloys or superalloys have traditionally been investment cast in ceramic molds to attain precise castings with little interaction of the molten metal with the mold material.
Investment casting can be a complex, expensive, and time-consuming process full of waste and is prone to error. High-temperature die casting is also difficult, given the relatively narrow available superheating range and the resulting tendency toward defects, shrinkage, and waste. In addition, traditional die casting results in equiax solidification from the die surface toward the center of the casting. This greatly complicates more specialized die castings requiring careful temperature control, such as single crystal (SX) castings and castings with columnar grain orientations formed via directional solidification (DS).